Assemble all your ingredients so once you start to slice the potatoes you can work quickly before they start to turn brown.

Spray a 9 X 11" casserole dish with deep sides. 4 " deep is good.

Using a mandolin or the slicing disc of your food processor cut the potatoes into thin slices. When you have the first 3 potatoes sliced spread the slices in the bottom of the baking dish. Sprinkle ⅓ of the flour evenly over the slices, the , place ⅓ of the butter pat around the dish and with a tablespoon place ⅓ of the condensed soup around the dish as well. Sprinkle with salt and pepper. Repeat twice more with ⅓ of the remaining potatoes, flour, butter, soup and salt and pepper each time.

Pour milk over the dish until you see the milk at the top edge of the potatoes. You should still have an inch or so of the side of the dish above the potato/milk mixture. The milk has a tendency to boil over the edge of the dish so either use a deep dish and/or place a baking sheet below the casserole while it is baking to catch drips.

Bake the casserole 80-90 minutes until the center is tender to a fork. The top will get dark brown. Cover loosely with foil if you think it is getting too dark.

Remove from oven and serve immediately.

This dish keeps well in the fridge for a day. To reheat, cover with foil and warm at 325 degrees about 40 minutes.